In dentistry, there has been a shift in recent years from a philosophy of drilling and filling to one of prevention and cosmetics. By way of example, many people today are choosing to have clinical procedures done to enhance their smile and appearance. Most of these procedures involve the modification of tooth shape, alignment, and/or color.
The use of intraoral video and/or imaging systems (hereinafter "intraoral camera system") has grown rapidly in dentistry over the past few years. Such systems are widely utilized in "show and tell" settings, i.e., where the dentist can show and illustrate particular features of a patient's mouth. These intraoral camera systems are rapidly becoming key complex diagnostic and treatment planning. Presently, approximately 30% of the practicing dentists in the age group between about 35-54 own and utilize intraoral camera systems. It is expected that that percentage will only increase with increased familiarity. See Dental Procedures Report, pgs. 22-24, February 1995.
A necessary step in altering a patient's tooth color is to determine the "shade" of the existing tooth. For example, those persons seeking a whiter, brighter smile are still assessed to establish their existing tooth color so that an appropriate before and after comparison can be made. Shade determination is even more important for those persons seeking reconstructive work, since one goal of the reconstructive process is to achieve a natural appearance. Therefore, it is important to know the existing tooth shade so that it can be accurately matched with the new restoration.
The dental profession utilizes standardized shade guides created by those companies which manufacture the reconstructive materials. One well-known shade guide is the Vita.TM. shade guide, which includes sixteen different shades. Other, less popular shade guides include those guides provided by Bioform.TM. and SR-Vivadent.TM..
These shade guides are utilized in a rudimentary fashion. The guide itself is a plastic plate with a plurality of removable color tabs that are shaped like a tooth, e.g., the front tooth. Typically, to assess a patient's tooth shade, a dentist removes one of the colored tabs and holds it up to the patient's tooth so that she can "eyeball" the closest match possible. Understandably, there are many variables to this method, some of which stem from the subjectivity of the dentist making the eyeball assessment.
Once the tooth shade is determined, the information is used relative to the particular procedure needed. In bonding or filling a tooth, for example, the composite materials required for the restoration arc specified within the range of the shade guide, e.g., one of sixteen shades for the Vita.TM. range. More particularly, if a crown, bridge or denture is needed, the patient's shade must be determined and communicated correctly to the lab that make the crown, bridge or denture.
The communication of shade information between the dentist and the lab is extremely important. Often, there is a break-down or failure in this communication, resulting in a poor shade match for the patient. In some cases, a particular dentist utilizes an uncommon shade guide, thereby leaving the lab technician to eyeball and convert the shade information to a Vita standard shade (since porcelain is often made from the Vita.TM. shade guide). This too can result in improper shade matching.
The process for selecting the porcelain for a particular tooth shade illustrates the difficulty in assessing and manufacturing the correct color match. If, for example, a crown of Vita.TM. shade A3 is desired, porcelain is built by hand with a paint brush onto a model of the tooth to be restored. The porcelain is built in layers on the model to achieve translucency and natural appearance. Each layer has a particular color and intensity associated with it. To generate shade A3, the technician follows a "recipe" that is given by the manufacturer Vident.TM., requiring a different shade for each layer of porcelain applied. If a doctor asks for a shade that is not a Vita.TM. standard shade, the technician typically seeks to achieve that shade by combining different porcelain shade combinations together, to increase or decrease the chroma, hue and value of the shade.
To further complicate the color-matching process, some dentists are simply not skilled in taking and determining shade information. Therefore, these dentists sometimes send their patients directly to the lab where the technician can determine the shade information. Alternatively, these dentists sometimes have a technician come to their office. In either event, there is, at times, one more level of subjective uncertainty injected into the correct match and determination of a patient's tooth shade. Thus, there is a need for more improvements in this area.